SAP PI BPM

Hello! Friends, need to make a BPM process to send messages to the recipient's working server. the recipient has a primary server and a secondary one and if the main one does not work for some technical reasons, then they raise the secondary server and therefore there is a need to send a message to the server that is in this case a worker.

The scheme is as follows:

ERP (Sender) - SAP PI - BPM - SAP PI - Receiver

At this stage I only have a block Start and End :) what other blocks should I use to get success? Help please create a process to send messages to the secondary server if the primary does not work.